A series of images are produced prior treatment to assure that patient’s position is exactly as it was at the time of the CT scan. This is done using a kV CT scanner attached to the LINAC that obtains real-time 3D images of the patient (called cone beam CT). Thus, IGRT aid the accuracy of beam direction since beam positioning can be checked and verified prior treatment delivery.
A 3D conformal radiation treatment shapes the radiation beams to closely fit the area of interest. This allows the exact targeting of the tumour and the delivery of minimal dose to the surrounding normal tissue.
IMRT is a type of conformal radiotherapy, which is used to treat complex treatment volumes. The basis of this technique is the use of intensity modulated beams that can provide various intensity levels of radiation. Thus, different doses of radiation are delivered across the tumour. This technique is planned using inverse planning algorithms; ensuring conformity and dose homogeneity to the tumor while spearing close proximity organs at risk.
This is an advanced type of IMRT. The machine rotates around the patient during radiotherapy in an arc shape and continuously reshapes and changes the intensity of the radiation beam as it moves, enabling faster treatment delivery.
It is a highly precise technique for irradiation of intracranial tumors. It enables the delivery of high dose of radiotherapy with a very steep dose gradient outside the tumor. The high precision of the dose delivery resembles the precision of a surgical scalpel; this is why this technique is also referred as radiosurgery. It is an alternative to the surgical resection of brain metastases.